“I wish I knew,” coach Claude Julien said of his team’s failure to launch. “That first period was an important period for us. It didn’t work out that way.”

Be it via French press, pour over, or simply a full hot pot down their pants, the Bruins need some caffeine in their legs, in their heads, and up their backsides when the puck drops Thursday night.

Defensively, their brains were on lockdown. The neutral zone, which is a critical launch pad for the Bruins, sucked away their energy. In the offensive zone, the Bruins repeatedly lost battles and races for the puck, mostly because they couldn’t rev up their wheels in center ice.

The result: a three-goal crevasse from which the Bruins never emerged.

“Our team just wasn’t good enough at the start to give ourselves a chance,” Julien said. “We need to rebound here and make sure that we’re ready from the start of the game at the drop of the puck.”

There were no bigger culprits than Milan Lucic and Jarome Iginla, the team’s supposed strongmen. The Canadiens don’t have a shutdown monster like Zdeno Chara to neutralize the wingers’ speed and strength in the danger areas. When the puck is on their sticks, Lucic and Iginla should not have any impediments toward getting to their offices down low behind the defensemen.

But they never had the puck. After 20 minutes, when the Canadiens held a 2-0 lead, Lucic and Iginla had combined for zero shot attempts.

Chase, chase, chase.

Lose, lose, lose.

Defensive mistakes happen to any team. A botched exchange between Tuukka Rask and Kevan Miller mushroomed into an all-out scramble in the defensive zone. Because the Bruins were pursuing the puck, they left Tomas Plekanec open at the far post. Thomas Vanek had all day to hit Plekanec for the game-opening goal at 10:57 of the first. Like any good team, the Canadiens turned their opponents’ bad bounces into a goal.

The Canadiens, however, gave the Bruins some daylight. P.K. Subban was sent off for roughing at 12:38 when he clobbered Reilly Smith and Vanek. But the Bruins did nothing on the power play. They didn’t land a single puck on Carey Price.

It was two minutes of gear-grinding. Then it got worse.

Dougie Hamilton had to be aware that Subban’s penalty was about to expire. Had Hamilton recognized the situation, he would have bailed out and marked Subban as he left the box. Instead, Hamilton pursued Lars Eller — Patrice Bergeron had a slack gap, but was in containment — and forgot about Subban.

At 14:44, Subban made Hamilton pay.

“I thought our lack of awareness really ended up costing us tonight,” Julien said. “As usual, we kind of battled back and got ourselves back in the game. But certainly we dug ourselves too big a hole to get out of tonight.”

It wasn’t until early in the second period that the Bruins found their game. They carried the puck over the offensive blue line with speed and numbers. As usual, this led to chances. The best opportunity came when Daniel Paille spotted Carl Soderberg open in front. Price was out of position. But Paille’s pass thudded off Soderberg’s left skate.

The Bruins’ momentum flat-lined after Dale Weise’s game-winning goal. Mike Weaver’s block of Andrej Meszaros’s shot led to Daniel Briere springing Weise for a breakaway. Weise cracked a haymaker off the Bruins’ jaw by beating Rask at 13:52 of the second to give his team a 3-0 lead.

The Canadiens executed their blueprint perfectly. Price (26 saves) stopped the pucks he was expected to turn back. The Canadiens counterattacked by stretching out the Bruins.

After the Bruins handed Montreal a three-goal lead, the Canadiens gummed up the real estate in front of Price. They gave the Bruins no room to breathe. With five men jamming down low and in the slot, the Bruins couldn’t breach Montreal’s secure perimeter. The Bruins attempted 18 third-period shots, but the Canadiens blocked nine of them. Only seven pucks slipped through Montreal’s protection. One eluded Price during six-on-five play — a Meszaros snapper that was tipped in by Iginla.

Montreal’s approach was boring. It was passive. It worked.

“It certainly was a big boost,” Montreal coach Michel Therrien said of his team’s good start. “We got out of the gate again tonight, we took the lead, and we were playing the lead. I liked the way we played the third period. We only allowed seven shots. That’s something we’ve done all year long. We played with the lead and made sure we finished the job.”

The Bruins pushed for several shifts at the start of the third. But they faded for the rest. They had burned too much gas trying to come back.

If the Bruins go ahead in Game 4, Montreal can’t sit back and play pack-it-in defense. The Canadiens will have to pull out of shooting lanes, blow the zone, and look for offense. In the brief segments this has happened during the series, the Bruins have laughed off Montreal’s offensive pressure. The Canadiens rarely have cycled with purpose. They haven’t ripped off second or third attempts on Rask.

But the Canadiens haven’t had to. They’ve been happy with unwrapping the early gifts the Bruins insist on giving them.